Three-Layer Inter-Electrode Insulating Film for Non-Volatile Memory
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Solution Overview
Problem
Current non-volatile semiconductor memory devices face challenges in minimizing memory cell leakage and threshold voltage shifts due to the diffusion of metals and defects in the inter-electrode insulating films, which affect the storage and retrieval of charges.
Innovation Solution
A non-volatile semiconductor memory device configuration that includes a three-layer inter-electrode insulating film structure with a lower layer, intermediate layer, and upper layer, where the intermediate layer has a higher barrier height and contains a first element with a varying ratio relative to a second element, preventing metal diffusion and reducing defects, and a floating gate electrode with a three-layer structure to manage charge accumulation and leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a high-dielectric film is used as an inter-electrode insulating film to address miniaturization of memory cells, then the memory cell size is reduced, but metal diffusion and defects in the insulating film increase, causing charge leakage and threshold voltage shifts
Solution Approach 1:
The inter-electrode insulating film is divided into three distinct layers: a lower layer insulating film, an intermediate insulating film, and an upper layer insulating film. Each layer has specific compositional characteristics that work together to prevent metal diffusion while maintaining miniaturization benefits.
Solution Approach 2:
The lower layer insulating film has a composition that varies through its thickness, with a first element to second element ratio that is larger on the side closer to the intermediate insulating film than on the side closer to the floating gate electrode. This local compositional variation optimizes both diffusion prevention and electrical performance.
2Productivity
If the inter-electrode insulating film is miniaturized to increase storage density, then more memory cells fit in the same area, but metal diffusion becomes more significant, causing threshold voltage shifts
Solution Approach 1:
The intermediate insulating film acts as a mediator between the lower and upper layer insulating films, providing an additional barrier against metal diffusion and helping to maintain precise threshold voltage control in miniaturized memory cells.
Solution Approach 2:
The inter-electrode insulating film uses a composite structure with three layers having different compositions and properties, combining the benefits of each material to achieve both high storage density and precise voltage control.
3Device complexity
If a simple single-layer insulating film is used, then the device structure is simpler and manufacturing is easier, but it cannot effectively prevent metal diffusion and charge leakage
Solution Approach 1:
The insulating film is segmented into three functional layers, each targeting specific harmful effects: the lower layer provides the primary diffusion barrier, the intermediate layer enhances protection and provides compositional transition, and the upper layer completes the insulating structure.
Solution Approach 2:
The composition parameters of the insulating film are changed through the three-layer structure, with the lower layer having a specific first element to second element ratio that varies through its thickness, optimizing the balance between diffusion prevention and electrical characteristics.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces charge leakage and shifts in threshold voltage by controlling the diffusion of metals and defects, enhancing the reliability and efficiency of memory cell operations.
Implementation Method 1
The intermediate insulating film contains a first element. The lower layer insulating film contains the first element and a second element, such that a ratio of the first element relative to the second element is larger on a side closer to the intermediate insulating film than on a side closer to the floating gate electrode.
Implementation Method 2
The intermediate insulating film contains a first element. The lower layer insulating film contains the first element and a second element, such that a ratio of the first element relative to the second element is larger on a side closer to the intermediate insulating film than on a side closer to the floating gate electrode.
Data Source
AI summary
According to one embodiment, an inter-electrode insulating film interposed between a floating gate electrode and a control gate electrode includes a lower layer insulating film disposed on a side closer to the floating gate electrode, an upper layer insulating film disposed on a side closer to the control gate electrode, and an intermediate insulating film interposed between the lower layer insulating film and the upper layer insulating film, wherein the intermediate insulating film contains a first element, and the lower layer insulating film contains the first element and a second element, such that a ratio of the first element relative to the second element is larger on a side closer to the intermediate insulating film than on a side closer to the floating gate electrode.